A high pressure pump, which pressurizes fuel to be supplied to an internal combustion engine, is known. The high pressure pump pressurizes the fuel, which is supplied from a supply passage to a pressurizing chamber. Thereafter, the high pressure pump discharges the pressurized fuel, which is pressurized in the pressurizing chamber, through a discharge passage.
For instance, JP2012-251658A (corresponding to US2012/0288389A1) discloses such a high pressure pump, which includes an inner flow path and an outer flow path. The inner flow path is formed in a valve seat member, which partitions between a supply passage and a pressurizing chamber. The outer flow path is configured into an annular form and is placed on a radially outer side of the inner flow path. In this way, a passage cross-sectional area (an opening area) of the entire flow path, which communicates between the supply passage and the pressurizing chamber, is increased. Thus, a required lift amount (i.e., a required amount of lift) of a valve element, which is required to ensure the required amount of the flow to be supplied to the pressurizing chamber, can be reduced. Thereby, the acceleration of the valve element at a valve opening time or a valve closing time thereof is reduced, and a collision speed of the valve element against the valve seat or a stopper is reduced. Thus, the collision impact force of the valve element against the valve seat or the stopper is reduced, and the vibration conducted to a surrounding area, which is located around the valve seat or the stopper, is reduced. Thus, the noise, which is outputted from the high pressure pump to the outside, is reduced.
However, in the high pressure pump of JP2012-251658A (corresponding to US2012/0288389A1), the valve seat, which is formed in the inner flow path, and the valve seat, which is formed in the outer flow path, are opened and closed by the single valve element. Therefore, in a case where the valve seat of the inner flow path and the valve seat of the outer flow path are no longer present in a common plane due to, for example, wearing that is induced by a temperature change of the high pressure pump or an increase in the number of operations of the high pressure pump, a small gap may possibly be formed between the valve seat of the inner flow path and the valve element or between the valve seat of the outer flow path and the valve element. When the pressurized fuel, which is pressurized in the pressurizing chamber, is leaked to the supply passage through this gap, the pump efficiency of the high pressure pump may possibly be deteriorated. Furthermore, when the small gap is formed between the valve seat and the valve element, cavitation may possibly occur in the high pressure fuel conducted through the gap, and this cavitation may possibly cause erosion of the valve seat and the valve element.